The Radiographic Approach to the Coughing Dog

Matthew Cannon, DVM DACVR

Pixel Veterinary ImagingAustin, TX

Environment

• Set yourself up for success– Diagnostic quality radiographs– Visual interpretation

• Ambient lighting• Appropriate display

– Consistent approach• All structures evaluated• Systematic and repeatable process

– Organization of thoughts

Potential Sources

• Pulmonary parenchyma– Lung patterns

• Heart• Trachea• Mediastinum• Pleural space

Donuts and Tramtracks, Oh my!

• Bronchial Pattern – Airway inflammation!!!– Chronic bronchitis– Age-related change– Infectious disease

• Parasitic (heart/lungworm)• Fungal (less likely)

– PIE – Irritant (smoke)– Allergic

Trees in the Fog – A Davis Winter

• Alveolar Pattern– Bronchopneumonia– Edema– Atelectasis– Hemorrhage– Mass – Histiocytic sarcoma– Torsion/infarct

• Location and character Air bronchogram

Lobar Sign

Surrounding Vessels

Alveolar Pattern Not an Alveolar Pattern!

Interstitial PatternUnstructured• Underexposure• Underinflated lungs• Obesity• Age-related changes• Disease in transition

– Edema– Hemorrhage– Bronchopneumonia

• Lymphoma• IPF in terriers• Pneumonitis

– Parasitic– Viral pneumonia– Inhalation (smoke, etc)– Toxic (paraquat)– Metabolic (uremia, etc)

Structured (nodular)• Neoplasia

– Primary lung tumor– Metastasis

• Granuloma– Fungal– Eosinophilic– Parasitic

• Abscess - FB• Bulla• Hematoma• Mucus-filled bronchus• Artifact

Unstructured Interstitial Pattern

• Description– Generalized increased opacity– Hazy– Poorly-defined vascular borders

• Non-specific pattern– MUST correlate to clinical signs

Miliary Pattern

Miliary Pattern

Vascular Pattern

Pulmonary Parenchyma

• Rules to live by:– The predominant (and worst) pattern wins– Not every pattern is clear– Interstitial is everything else– Three views for all– Don’t forget the cervical region

Bronchointerstitial Pattern

Heart versus Lung Disease• Important Questions:

– Degree of cardiomegaly?• Exception: ruptured chordae tendinae

– Enlarged pulmonary vessels?– Left atrial impingement on airways?– Auscultation findings?

Ruptured Chordae Tendinae - Before

Ruptured Chordae Tendinae - After

Trachea• Trachea

– Anatomy– Collapse– Displacement/Compression– Stricture

• Neoplasia, granuloma, fibrous, FB, polyp

– Tracheitis• Very common clinically• Poorly identified on rads

Tracheal Anatomy

Breed Differences

Tracheal Collapse• Chondromalacia

– Often seen in association with:• Mainstem bronchi collapse• Lower airway inflammation – chronic bronchitis

• Fat old small breed dogs• Redundant tracheal membrane

– Exception – Grade I “collapse”• Dynamic process

– Lack of radiographic sensitivity– Mainstem bronchi– Fluoroscopy

Redundant Tracheal Membrane

Tracheal Displacement/Compression

Tracheal Stricture

Mediastinum• Anatomy• Cause of Coughing

– Mass• Neoplasia – Lymphoma, thymoma• Hemorrhage (rodenticide)• Granuloma – crypto (esp. cats)• Branchial cyst

– Hilar lymphadenopathy• Lymphoma, fungal, PIE

– Mediastinal Shift• Atelectasis

Anatomic Differences

Mediastinal Reflections

Mediastinal Masses• Causes cough by tracheal impingement• Cranial Mediastinum

– Radiographic signs• Widened mediastinum (DV/VD)• Tracheal deviation

– Dorsal or lateral• Caudal cardiac/hilar deviation

– Normal: 5th/6th thoracic vertebra level• Pleural effusion

– Often seen with mediastinal masses– Should not cause tracheal elevation by itself (dogs)

Hilar Lymphadenopathy

• Radiographic findings:– Cowboy sign– Increased perihilar density– Deviation of the trachael carina

• Usually ventral or unchanged

• Hilar lymphadenopathy vs large LA– LA: dorsal tracheal elevation– LA: overall heart size is also increased

Hilar Lymphadenopathy

Cowboy Sign Mediastinal Shift

Pleural Space

• Pleural disease alone• Underlying pulmonary disease process

– Pyothorax• FB pneumonia• Pulmonary abscess (hematogenous, penetrating)

• Neoplasia• Lung lobe torsion/infarction

Question!

• Feel free to contact me anytime:– cannon.vetrad@gmail.com– 512-534-8414– Pixelvetimaging.com